This invention relates to a ground excavation apparatus and more particularly to a cutting edge member for fitting on an excavation apparatus.
Excavation machinery such as "backhoes" and "ditch-diggers" are well known in the art for digging up ground to carry out various jobs, for example, forming a cavity for laying pipeline or uncovering existing buried pipeline. Such machinery is also used for digging around pipelines for maintenance on other nearby equipment.
Typically, excavation machinery such as a backhoe have an "arm" with a "bucket" attached to the end of such arm for cutting, digging or scooping away ground covering to form a cavity in the ground. The cutting edge of the bucket used for cutting the ground, may have a plurality of sharp projecting parts or "teeth" for aiding in digging up the ground or the bucket may have a straight edge (without teeth) for cutting the ground.
The teeth or straight edge making up the cutting edge of the bucket of backhoes and ditch-diggers are, typically, made from hard steel. The cutting edge can easily rupture most pipelines. Excavation near underground pipelines containing flammable fluids such as high vapor pressure hydrocarbons, e.g., liquid propane gas (LPG), is very hazardous when performed with a machine such as a backhoe because the bucket cutting edge can rupture such pipeline and a subsequent explosion of the flammable gas can occur caused by an ignition source such as a spark from friction of the cutting edge contacting the pipeline or by the engine of the backhoe. Moreover, when the precise location of the pipeline carrying flammable fluids is not known, the cutting edge of the excavating machine is apt to strike the pipeline. If the pipeline is ruptured, an uncontrolled release of flammable hydrocarbon vapor into the surrounding atmosphere may occur. This type of accident usually results in loss of life and extensive property loss.
It is desired, therefore, to provide a tool useful as a cutting edge member for fitting onto an existing cutting edge of excavation machinery which will be of sufficient hardness to dig through ground covering but will not damage steel pipelines when the pipeline is struck with such cutting edge during excavation.